crypto: caam - staticize caam_get_era()

caam_get_era() is only used locally, so do not export this function
and make it static instead.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/ctrl.h

@@ -9,8 +9,6 @@
 #define CTRL_H
 
 /* Prototypes for backend-level services exposed to APIs */
-int caam_get_era(void);
-
 extern bool caam_dpaa2;
 
 #endif /* CTRL_H */